"This is a conspiracy against me. I have never taken any banned substance," said Narsingh.
Narsingh, who was picked ahead of the double Olympic medallist Sushil Kumar to represent India at the Rio Games in 74kg Freestyle category, has been handed provisional suspension and virtually ruled out of next month's Olympics.
The 26-year-old wrestler's Olympics accreditation has also been withheld.
The Wrestling Federation of India (WFI) has also cried foul, claiming that Narsingh has a clean history and it seems to be a sabotage.
"It is a sabotage, foul play. Narsingh has a very clean history. It's clearly a conspiracy against him," WFI sources said.
Narsingh's chances of going to Rio look bleak but even Sushil Kumar is set to miss the flight.
"Decision on the representation in 74kg is to be taken later but in all likelihood there would be no Indian representation in 74kg category in Rio Games because the date of entry of the athletes is over," the source added.
Narsingh, who won the 74kg Olympic quota berth with a World Championships bronze last year, was selected by the WFI to represent India at the Rio Games in controversial circumstances after Sushil's demands for a trial were rejected by the Federation as well as the Delhi High Court after a lengthy legal battle.
National Anti-Doping Director General Navin Agarwal confirmed that Narsingh's 'B' sample also tested positive for a banned substance and he appeared before a NADA disciplinary panel yesterday. Sources said that he had returned positive for methandienone -- a banned anabolic steroid.